Ballasts are an integral component of the lighting industry and are either magnetic or electronic. Magnetic ballasts utilize components which are heavy and cumbersome, while electronic ballasts use electric circuits on a light-weight and reduced size circuit board. A ballast may be used to start a high density discharge (HID) lamp, and regulates electrical current used by the lamp. HID lamps are identified by the gas within the lamp—metal halide (MH), high-pressure sodium (HPS) or mercury vapor (MV)—and the gas affects the color of the light. Buyers choose a specific HID lamp based on the color, input voltage, output wattage and the starter (regular or pulse start).
There are two categories of HID ballast: magnetic and electronic. Magnetic ballasts, also called “core and coil” ballasts, dominate the HID market. Although inexpensive, magnetic ballasts flicker, are noisy and weigh as much as 86 lbs. Ballast manufacturers have redesigned their products to reduce electronic interference and noise, and lamp manufacturers have introduced pulse-start lamps to shorten the slow start times. Despite these improvements, magnetic ballasts are still energy-inefficient. Regulatory actions and fines threatens the long-term outlook for magnetic ballasts and, as they fail, many are being replaced with electronic ballasts.
Electronic ballasts may be 30–50% more energy-efficient than magnetic ballasts and deliver a relatively non-flickering, silent light, reduce the problem of magnetic interference, and may weigh less then 8 lbs. Until now, however, most electronic ballast manufacturers have followed a short-sighted, one-to-one design approach, requiring a unique electronic ballast for every input voltage, output wattage and lamp type combination. As an example, a 400 watt GE lamp works at optimal efficiency generally with only one particular ballast, whether the ballast is magnetic or electronic. If the ballast and lamp are not compatible or matched, the operation of the lamp will not be efficient, thereby adversely affecting brightness and the life of the lamp. Additionally, in the case of magnetic ballasts, each ballast has to be specifically wired for each lamp voltage input, such as 100V, 120V and so forth. Such wiring is accomplished at the manufacturer's factory or the end user is required to wire the ballast for each lamp depending on application. Therefore, a different ballast is required for each input voltage. These manufacturers often also sell dimmers, timers and controllers as separate, auxiliary components, to be used with their particular ballast design.